What values do the --verbose and --debug-value options accept?
Both these arguments are mainly for developers.


--verbose is currently only used by libmv (camera tracking), however we will likely use in the future to control other output.
--debug-value is mainly for developers to test alternative behavior, from Python you can access it from bpy.app.debug_value from C/C++ you can access it from G.debug_value (with BKE_global.h include).


For example --debug-value 2 makes the manipulator rotation handles draw differently.

For verbose logging with camera tracking use --verbose 2.